1. Field of the Invention
The present invention relates to a battery charger cradle, on which battery built-in devices such as a battery pack and a mobile phone can be placed, to recharge a built-in battery when electric power is carried by the effect of electromagnetic induction.
2. Description of the Related Art
A battery charger cradle has been developed for recharging a built-in battery, where electric power is carried from a primary coil to an induction coil (a secondary coil) by the effect of electromagnetic induction. Refer to Japanese Patent Laid-Open Publication No. H09-63655 (1997) and Japanese Utility Model Registration No. 3011829.
Described in Japanese Patent Laid-Open Publication No. H09-63655 (1997) is a structure in which the primary coil excited by an AC power source is incorporated in the battery charger cradle and the induction coil electromagnetically coupled to the primary coil is incorporated in a battery pack. The battery pack also incorporates a circuit in which an alternating current induced to the induction coil is rectified and supplied to the rechargeable battery for a charging operation. In accordance with such structure, the battery pack is placed on the battery charger cradle so that the battery contained in the battery pack can be recharged in a non-contact state.
Japanese Utility Model Registration No. 3011829 describes a structure in which the battery is contained in the bottom of the battery built-in device and a secondary-side charging adaptor is provided subjacently to the battery so that the induction coil and charging circuit are incorporated in the secondary-side charging adaptor. Also described is a structure in which the primary coil electromagnetically coupled to the induction coil is provided in the battery charger cradle. The battery built-in device coupled to the secondary-side charging adaptor is placed on the battery charger cradle, and the electric power is carried from the primary coil to the induction coil to recharge the battery contained in the battery built-in device.